Hundreds of drivers have been stranded for hours overnight in Kent and Sussex after the abrupt return of winter conditions caught out the Highways Agency for the first time since its gritting and ploughing system was beefed up last year.

Collisions and breakdowns prevented many of the fleet of 500 emergency trucks from reaching iced-up stretches where queues eventually stretched back as far as 30 miles with cars and lorries stuck for up to 10 hours.

The Met Office's yellow "be aware" warning cloaks all but the western coastal areas of the UK and the forecast is for ice, renewed snow and sleet, more of the same on Wednesday and no return to warmer conditions until the weekend.

Most of the rest of the UK escaped disruption but was left shivering in the coldest conditions in March since 1986. The lowest temperature overnight was at Saughall, in south Lanarkshire, which recorded -12C (10F). Northern England had clear skies and bright sunshine on Tuesday but was bitterly cold.

Those caught out by the south-east snowfall included a group of 120 German students who were put up overnight at Hastings town hall as temperatures fell to -3C (27F), with volunteers working in shifts to provide bedding and hot drinks.

The worst-affected roads included the M23, A23, A26, A27 and A29, which were all hit by about 10cm (4in) of snow.

Gatwick airport worker Jonathan Lara told the BBC it had taken him eight hours to creep along eight miles of his commute home to Brighton.

"It looks like the gritters have been totally caught out by this," he said, from his car. "I've been stuck in the same place for about three and a half hours now and it looks like I'm going to be here for hours yet."

Another stranded driver described zig-zagging desperately between abandoned cars to maintain speed and headway as "like driving through some sort of apocalypse".

The singer Cheryl Baker tweeted from a benighted expedition to collect her children, which normally takes an hour: "So 8 hours later, STILL stuck on the A25. Could have flown to NY by now. Was it the wrong kind of snow?"

The Highways Agency said the weather had been expected and emergency vehicles were stationed at six places in the south-east to go into action straight away. But accidents and breakdowns had combined with very strong winds and drifting to frustrate road-clearing.

"We have been working throughout the night with our partners in the emergency services and local authorities to respond to hundreds of incidents which took place in the heavy snow and strong winds," the agency said. "We treated our roads continually throughout the afternoon and during the night, but a large number of incidents, including heavy goods vehicles breaking down on hills, caused closures at several locations. As a result, a number of our salt spreaders and recovery vehicles then became caught in the traffic.

"Strong winds, gusting at speeds of up to 50 miles an hour, created snow drifts of up to a metre in height, in many cases blowing snow back on to the carriageway as soon as it had been cleared. As part of our emergency response we used pre-positioned heavy recovery vehicles in six locations in the south-east from 6pm onwards to help with blockages on the roads.

"In locations where blockages were cleared we were able to dedicate gritting crews to specific stretches of road where the weather was at its worst and to get queuing traffic moving again. The welfare of people caught in the queues elsewhere has been paramount and traffic officers and our colleagues in the emergency services have been making contact with people to ensure their wellbeing."

The agency said further snow was expected in the two counties and only essential road journeys should be attempted. The South East Coast ambulance service was using four-wheel drives to get essential staff to work.

The scale of chaos due to just one miscalculation was shown on the A2 at Lydden near Dover, where a jack-knifed lorry left more than 100 people stuck for four hours. Kent police said that ferry and Channel tunnel traffic was caught up in exceptional bottlenecks, including the familiar troublespot of the M20.

Acting Chief Inspector Kay Maynard said: "We know how difficult it has been for many people who felt stranded in their vehicles. We have been trying to get to as many as possible to offer reassurance, as well as deal with the problems on the roads caused by collisions and broken down vehicles.

"The volume of snow and the drifting caused in exposed areas has been a major issue. As soon as roads were cleared and gritted, they were becoming covered in snow again."

Inspector James Biggs, of Sussex police, said the force's officers had worked throughout the night at full capacity alongside the Highways Agency, with the worst-affected area being the A23 and M23 near Handcross Hill.

"Officers are assisting the gritters to try to get them to these areas as soon as possible," he said. "If drivers could assist us by allowing the gritters through the congestion as much as possible this would be greatly appreciated. Many drivers have been rescued but I know many more have endured long hours stuck in their vehicles."

Rail and air travel in the south-east faces delays all day, with cancellations on major commuter routes to and from Brighton and Eastbourne.

All Eurostar services have been cancelled on Tuesday by the bad weather on the continent rather than in south-east England, where lines were operational. Trains have been unable to run in parts of France and Belgium.

Trains between London and Brighton have been reduced to an hourly service, with other delays in Essex, the West Midlands, and between Barry and Cardiff in south Wales. Southern trains have warned of short-notice cancellations and delays of up to 60 minutes across the company's network.

The Channel Islands are recovering from a similar dumping of heavy snow but Jersey airport remains closed.

The biggest daffodil festival in the UK held in March at Thriplow in Hertfordshire faces a delayed launch next year after four years running with meagre entries because of winter weather. This year's will go ahead as planned the weekend of 16 and 17 March, but without daffodils in flower because the chill has left most a month behind.